This proposal is for continuation of research into the natural history, treatment, and epidemiology and the statistical conduct, design, collation, and publication in childhood cancer. It will continue to emphasize multimodal aspects of the Children's Cancer Study Group which has realized such excellent results in the past in Wilm's tumors, rhabdomyosarcomas and now Ewing's sarcomas, a member of the intergroup study. This approach should greatly enhance studies in brain tumors, Hodgkin's disease and non-Hodgkin's lymphoma in the near future. During the period July 1973 to October 1975, 241 new patients with malignant disease have been seen at this institution; 105 with leukemia and 136 with solid tumors. We have been a member of the Cildren's Cancer Study Group since 1959 and strong, permanent referral patterns have been established. It is, therefore, anticipated that this patient load will continue to increase over the next several years. A close working relationship with the Adult Leukemia Center under Dr. E. Donnall Thomas, now at the Fred Hutchinson Cancer Research Center, continues. This included exchange of professional personnel. This is illustrated by the fact that our personnel under the direction of Dr. Thomas have now carried out 21 bone marrow transplantations on children with acute leukemia and aplastic anemia at this institution. Collaborative studies with Drs. Karl-Erik and Ingegard Hellstrom will continue through Dr. Irwin Bernstein in working with immunologic methods in pediatric tumors. Continued cooperation in the local community has already been enhanced and wil continue to be so now that the Fred Hutchinson Cancer Center is under operation. This program is the Pediatric Oncology Unit of the Fred Hutchinson Center.